Until now, stainless materials made of a melted stainless have been widely known as a sintered electromagnetic stainless material obtained by sintering. Electromagnetic stainless materials are used, for example, as magnetic parts such as electromagnetic valves, injectors for injecting fuels and various actuators.
Recently, frequency during use and higher harmonic wave component for such magnetic parts have been increased. In accordance with this, for example, loss of electric power and generation of heat due to eddy current generated when alternate current is applied to an iron core having a coil wound around the core tend to increase. Furthermore, hysteresis loss included in iron loss, i.e., generation of heat for the hysteresis that is shown when the magnetic area of the iron core changes the direction of the magnetic field by alternating magnetic field is also not negligible.
As a technique relating to the above, a sintered electromagnetic stainless material containing Si together with Fe—Cr has been suggested. For example, a solid metal made of melted materials including Fe-13Cr-2Si as a main component, and a sintered electromagnetic stainless material having a composition of Fe-6.5Cr-(1.0 to 3.0)Si containing 1 to 3% by mass of Si are disclosed (see, for example, Patent Documents 1 and 2 and Non-patent Documents 1 and 2), and many of which are constituted by using chromium (Cr) as a main component. Furthermore, a technique in which a mixed powder obtained by mixing a Si powder with a Fe powder and the like is pressed to form into a predetermined shape and thereafter sintered is disclosed (see, for example, Non-Patent Document 3).
Meanwhile, in the case of a solid metal made of melted materials, it is necessary to perform processing such as cutting in order to obtain a desired shape and machine processing is inevitable, which is not advantageous for the steps. Therefore, a method in which a formed product having approximately a desired shape is directly obtained using a metal powder in order to readily obtain a desired shape in a short time period while decreasing mechanical processing (near net shape in which molding is carried out by powder metallurgical method) has been widely carried out.    Patent Document 1: Japanese Patent Application Laid-Open (JP-A) No. 7-76758    Patent Document 2: JP-A No. 7-238352    Non-Patent Document 1: Hitachi Powder Metallurgy Technical Report No. 5 (2006), p. 27 to 30    Non-Patent Document 2: Tohoku Steel Co., Ltd., product information (electromagnetic stainless steel), of record in the US Patent and Trademark Office prosecution history of U.S. Ser. No. 12/601,206 filed May 14, 2008.    Non-Patent Document 3: Hitachi Powder Metallurgy Technical Report No. 3 (2004), p. 28 to 32